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81.
ISHIWATARI Akira 《《地质学报》英文版》2015,89(Z2):33-34
<正>Plume-type is a new branch of ophiolite classification introduced by Dilek and Furnes(2011;GSAB,123,387-).Its most typical example is the komatiite-basalt-gabbrowehrlite assemblage that is exposed on the Gorgona Island off Colombia,South America and is interpreted as a part of the Caribbean large igneous province(LIP).Analogous 相似文献
82.
Akira Yamaguchi Takehiko Setoyanagi Mitsuru Ebihara 《Meteoritics & planetary science》2006,41(6):863-874
Abstract— We studied the texture, mineralogy, and bulk chemical composition of Dhofar 007, a basaltic achondrite. Dhofar 007 is a polymict breccia that is mostly composed of coarse‐grained granular (CG) clasts with a minor amount of xenolithic components, such as a fragment of Mg‐rich pyroxene. The coarse‐grained, relict gabbroic texture, mineral chemistry, and bulk chemical data of the coarse‐grained clast indicate that the CG clasts were originally a cumulate rock crystallized in a crust of the parent body. However, in contrast to monomict eucrites, the siderophile elements are highly enriched and could have been introduced by impact events. Dhofar 007 appears to have experienced a two‐stage postcrystallization thermal history: rapid cooling at high temperatures and slow cooling at lower temperatures. The presence of pigeonite with closely spaced, fine augite lamellae suggests that this rock was cooled rapidly from higher temperatures (>0.5 °C/yr at ˜1000 °C) than typical cumulate eucrites. However, the presence of the cloudy zone in taenite and the Ni profile across the kamacite‐taenite boundaries indicates that the cooling rate was very slow at lower temperatures (˜1–10 °C/Myr at <600–700 °C). The slow cooling rate is comparable to those in mesosiderites and pallasites. The two‐stage thermal history and the relative abundance of siderophile elements similar to those for metallic portions in mesosiderites suggest that Dhofar 007 is a large inclusion of mesosiderite. However, we cannot rule out a possibility that Dhofar 007 is an anomalous eucrite. 相似文献
83.
J. Tueller H. A. Krimm T. Okajima S. D. Barthelmy S. M. Owens P. J. Serlemitsos Y. Soong K.-W. Chan Y. Ogasaka R. Shibata K. Tamura A. Furuzawa Y. Tawara H. Kunieda K. Yamashita 《Experimental Astronomy》2005,20(1-3):121-129
InFOCμS is a new generation balloon-borne hard X-ray telescope with focusing optics and spectroscopy. We had a successful 22.5-hour flight from Fort Sumner, NM on September 16,17, 2004. In this paper, we present the performance of the hard X-ray telescope, which consists of a depth-graded platinum/carbon multilayer mirror and a CdZnTe detector. The telescope has an effective area of 49 cm2 at 30 keV, an angular resolution of 2.4 arcmin (HPD), and a field of view of 11 arcmin (FWHM) depending on energies. The CdZnTe detector is configured with a 12 × 12 segmented array of detector pixels. The pixels are 2 mm square, and are placed on 2.1 mm centers. An averaged energy resolution is 4.4 keV at 60 keV and its standard deviation is 0.36 keV over 128 pixels. The detector is surrounded by a 3-cm thick CsI anti coincidence shield to reduce background from particles and photons not incident along the mirror focal direction. The inflight background is 2.9 × 10−4 cts cm−2 sec−1 keV−1 in the 20–50 keV band. 相似文献
84.
Marc W. Pound Jave O. Kane Bruce A. Remington Dmitri D. Ryutov Akira Mizuta Hideaki Takabe 《Astrophysics and Space Science》2005,298(1-2):177-181
Over the past few years, our group has been developing hydrodynamic models to simulate formation of the Eagle Nebula pillars.
The true test of any model is, of course, how well it can reproduce the observations. Here, we discuss how we go about testing
our models against observations. We describe the process by which we “observe” the model data to create synthetic maps. We
show an example of this technique using one of our model runs and compare the resultant synthetic map to the real one. 相似文献
85.
Akira Takada C. R. A. Catlow G. D. Price C. L. Hayward 《Physics and Chemistry of Minerals》1997,24(6):423-431
The structure and electronic properties of trigonal and orthorhombic boric oxide (B2O3) are studied using periodic ab initio Hartree-Fock method. The optimised structural parameters for two B2O3 polymorphs are in good agreement with experimental data. The analyses of their electronic structures provide insights into the chemical nature of the B–O bond and the way in which it changes with the coordination number around boron and oxygen. Our quantum-chemical study suggests that the orthorhombic form is more ionic than the trigonal form and that the coordination number of boron around oxygen plays a more dominant role than that of oxygen around boron in B2O3 crystals. 相似文献
86.
Shinpei Shibata 《Astrophysics and Space Science》1989,161(1):145-158
A numerical method to determine the electromagnetic field of a steadily rotating magnetosphere with an inclined magnetic moment under a given boundary condition on an arbitrary shaped boundary surface is presented. The region may include the light cylinder. The present method, together with a companion method giving particle motion and creation, makes an iterative scheme to obtain a global model of the pulsar magnetosphere. A key problem for explaining the particle acceleration in pulsars is to solve field-aligned electric field in an accelerating region bounded by an ideal-MHD region. The present method is fit to connect a solution for the non-ideal-MHD region with another solution for the ideal-MHD region on a boundary surface whose location should also be solved (i.e., a floating boundary). The integration scheme is based on the boundary element method and it has great advantage as compared with other methods like the finite difference method and the Fourier transformation method. 相似文献
87.
J. Huang N. Hotta K. Kasahara I. Ohta S. Ozawa T. Saito M. Shibata X. W. Xu T. Yuda 《Astroparticle Physics》2003,18(6):637-648
We have done extensive Monte Carlo simulations using the new simulation codes of CORSIKA and COSMOS to compare with the gamma-family data obtained at Mts. Fuji (3750 m above sea level) and Kanbala (5500 m above sea level). Then, we estimated the primary proton and helium spectra around the knee energy region using a multiple-layered feed-forward neural network as a classifier of primary particle kind. The selection efficiency of proton-induced family events is estimated to be 82%. The flux value of protons at 2×1015 eV is (5.5±1.5)×10−14 (m−2 s−1 sr−1 GeV−1). The result suggests heavy-enriched primary composition around the knee region. 相似文献
88.
Abstract— Phase diagrams describing solid-gas equilibria in the system Fe-Mg-Si-O-C-H under H-rich conditions (~700–2000 K and 10?2–10?20 atm of Ph 2), including solar nebula conditions, were constructed based on thermochemical calculations. Boundaries of vaporous phases, which are the first phases to condense from a gas, can be obtained without calculating condensation temperatures of individual gas compositions because the numbers of major gaseous species are the same as those of components in the concerned systems. Fractionations by condensation and/or evaporation can be discussed easily in such phase diagrams. A thermal divide, which is a barrier that vapors cannot cross by a single cooling process, was recognized in the phase diagrams. This is present on the Fe-MgO-SiO2-CO-H plane at high temperatures (≥500–700 K) and plays an important role in fractionations. Oxidizing states of ordinary chondrites and carbonaceous chondrites before aqueous alteration are located at the O-rich side of the thermal divide. Such oxidizing states can be formed from the solar gas by fractionation in the primordial solar nebula because the solar composition is located on the O-rich side. On the other hand, the reducing states of enstatite chondrites, located at the O-poor side, cannot be formed as long as the thermal divide is present. The reducing states can be obtained by CO to CH4 molecular reaction at low temperatures (≤500–700 K), where the high-temperature thermal divide is absent. Addition of H2O-rich and CH4-rich ice can explain establishment of the redox states of ordinary and enstatite chondrites, respectively. 相似文献
89.
Yoshida A Nomura H Toyoda K Nishino T Seo Y Yamada M Nishimura M Wada M Okamoto K Shibata A Takada H Kogure K Ohwada K 《Marine pollution bulletin》2006,52(1):89-95
Microbial responses to the addition of oil with or without a chemical dispersant were examined in mesocosm and microcosm experiments by using denaturing gradient gel electrophoresis of bacterial ribosomal DNA and direct cell counting. When a water-soluble fraction of oil was added to seawater, increases in cell density were observed in the first 24h, followed by a decrease in abundance and a change in bacterial species composition. After addition of an oil-dispersant mixture, increases in cell density and changes in community structure coincided, and the amount of bacteria remained high. These phenomena also occurred in response to addition of only dispersant. Our results suggest that the chemical dispersant may be used as a nutrient source by some bacterial groups and may directly or indirectly prevent the growth of other bacterial groups. 相似文献
90.
We studied the relationships between streamwater chemistry and the topography of subcatchments in the Dorokawa watershed in Hokkaido Island, northern Japan, to examine the use of topography as a predictor of streamwater chemistry in a watershed with relatively moderate terrain compared with other regions of Japan. Topographic characteristics of the Dorokawa watershed and its subcatchments were expressed as topographic index (TI) values, which ranged from 4·5 to 20·4 for individual grid cells (50 × 50 m2), but averaged from 6·4 to 7·4 for the 20 subcatchments. Streamwater samples for chemical analyses were collected four times between June and October 2002 from 20 locations in the watershed. The pH of water that passed through the watershed increased from ~5·0 to 7·0, with major increases in Na+ and Ca2+ and marked decreases in NO3? and SO . Distinctive spatial patterns were observed for dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and NO3? concentrations of streamwater across the watershed. Statistical analyses indicated significant linear relationships between the average TI values of subcatchments and DOC, DON, and NO3? concentrations. Furthermore, the proportion of DOC in streamwaters in the wet season increased with TI values relative to other nitrogen species, whereas NO3? concentrations decreased with TI. The gradients of soil wetness and the presence of wetlands explained many of the observed spatial and temporal patterns of DOC, DON, and NO3? concentrations in the surface waters of the Dorokawa watershed. Our results suggest that the TI is especially useful for predicting the spatial distribution of DOC, DON and NO3? in the surface waters of Hokkaido, where topographical relief is moderate and wetlands more common than in other regions of Japan. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献